It can help, but if you don't know anatomy or lighting well enough to compensate for mistakes in the model, you are likely to get stiff, creepy-looking drawings. It's certainly not a substitute for life drawing. But it can be helpful in planning out a complex scene.
My initial attempts were quite stiff looking. I got around it by making many (horrible) pencil sketches of poses until I sort of feel how the subject should posture himself, the main action lines and shot composition. So later all I do in the 3D program is to fix things like shoulder positioning, relaxing the arm.
I'm not using the lighting haha, lighting is itself a very complex field in 3D so I'm not gonna touch it. With my method I'm mainly trying to solve issues with drawing foreshortening and perspective.
About the 3D program, I used Blender (which is free and partially recognised in the professional 3D industry) but I think there's the MikuMikuDance thing too, though I'm not too sure how it works.
The time to set up the scene is quite long though. I spent half a day in total googling for props and setting up the pose. I had prior experience with Blender, but I think one should be able to learn it in 2-3 weeks, since it's just moving their joints into position. Halfway through I had my doubts, but the results were well worth the time setting it up. The reference pic is not something I can Google for. A person with decent photographic ability (and a bunch of friends) might have an easier time than messing with 3D though.
the model itself, not very long, about 30 minutes of tweaking. If you know how to navigate to the bones and Pose mode, it's just a matter of rotating the bones into position. Each bone controls a joint (e.g. eyebrow, corner of mouth, ankle, hip).
IMO the hard part is actually finding the right model you want, like how tall, how muscular, drawing style (realistic, cartoon or anime).